1. Field of the Invention
This invention relates to a transmission for a motor vehicle, and more particularly to a transmission that can transmit torque from an engine and/or a generator and motor unit to an output shaft.
2. Description of the Related Art
Referring to FIG. 1, an in-series connection type conventional transmission for a motor vehicle is shown to include an engine 11, a generator 12, a rectifier 13, a storage battery unit 14, a converter 15, a motor 16, a speed reduction gear unit 17, an output shaft 18, and a controller 19. Power generated from the engine 11 activates the generator 12 to create alternating current that is passed through the rectifier 13 so as to be converted into direct current, which is stored within the storage battery unit 14. When it is desired to start the motor vehicle, the storage battery unit 14 supplies direct current, which is converted by the converter 15 into an electric current that can be utilized by the motor 16 so that the motor 16 can rotate the speed reduction gear unit 17 and thus the output shaft 18. The engine 11, the generator 12, and the converter 15 are controlled by the controller 19. A drawback associated with the aforesaid conventional transmission is that energy loss is relatively large during conversion between electric energy and dynamic energy.
To reduce the energy loss, an in-parallel connection type conventional transmission is developed. Referring to FIG. 2, the in-parallel connection type conventional transmission is shown to include an engine 21, a generator 22, a power distribution device 23, a speed reduction gear unit 24, an output shaft 25, a converter 26, a storage battery unit 27, and a motor 28. The engine 21 and the generator 22 are interconnected by means of the power distribution device 23. The power distribution device 23 is connected to the speed reduction gear unit 24 so as to transmit power to the output shaft 25. The generator 22 is connected to the storage battery unit 27 via the converter 26. The motor 28 is disposed between the converter 26 and the speed reduction gear unit 24.
Referring to FIG. 3, the power distribution device 23 is configured as a planetary gear unit, and includes a sun gear 231, four planetary gears 232, and a ring gear 233. The power distribution device 23 can transmit power from the engine 21 to the output shaft 25 via the speed reduction gear unit 24. The generator 22 can be activated by the power distribution device 23 to create and store electric energy within the storage battery unit 27. When the motor vehicle moves at a low speed, the engine 21 is stopped so that the motor vehicle is driven solely by the motor 28, thereby offering a comparatively large torque output to the output shaft 25. When the motor vehicle moves at a medium speed, it is driven solely by the engine 21. When the motor vehicle moves at a high speed, it is driven by both the engine 21 and the motor 28.
Both the generator 22 and the motor 28 are needed for the in-parallel connection type conventional transmission, thereby resulting in high manufacturing costs. Moreover, there is a need for high manufacturing precision and material strength of the power distribution device 23, thereby further increasing the manufacturing costs.
An object of this invention is to provide a transmission for a motor vehicle, which is inexpensive to manufacture.
Another object of this invention is to provide a transmission for a motor vehicle, which has a power distribution device that does not need high manufacturing precision and material strength.
According to this invention, a transmission for a motor vehicle includes a controller for controlling an engine, a generator and motor unit, a converter, and a storage battery unit. A detecting mechanism is used to detect the operating conditions of the motor vehicle and the engine so as to generate control signals. A power distribution device is disposed between the engine and the generator and motor unit. The generator and motor unit can be controlled to operate in one of a generator mode and a motor mode. As such, the generator and motor unit is cheaper than an assembly of a generator and a motor, thereby resulting in low manufacturing costs of the transmission.
In an embodiment, the power distribution device includes a belt and pulley unit that interconnects fixedly a motor shaft of the generator and motor unit and a high-speed output shaft.
In another embodiment, the power distribution device includes a connector that interconnects fixedly an end of the motor shaft and an end of the high-speed output shaft. As such, the power distribution device does not need high manufacturing precision and material strength.